The United States Consumer Product Safety Commission issued Standard for the Flammability (Open Flame) of Mattress Sets that establishes performance requirements (the “16 CFR 1633 requirements”) based on research conducted by the National Institute of Standards and Technology. Mattresses and mattress foundation sets that comply with the requirements will generate a smaller size fire with a slower growth rate, thus reducing the possibility of flashover occurring. During the test, the mattress or mattress set is located on top of a steel rig and exposed to two T-shaped burners with a total burner heat output of 27 kW. The side burner is applied for 50 seconds and the top burner is applied for 70 seconds. The fire is then allowed to develop freely. The smoke gases produced during the test are collected by a hood and exhaust system from where samples are taken for gas analysis. To meet the 16 CFR 1633 requirements, a mattress must maintain a heat release rate of less than 200 kW during the first 30 minutes of the test and, also, that the total heat release be less than 15 MJ in the first 10 minutes of the test.
Foam and latex mattresses are a challenge to meet the 16 CFR 1633 requirements. To meet the 16 CFR 1633 requirements, mattress manufacturers are using fire retardant fabrics to cover the mattress or mattress set. One type of fire retardant fabric for use as upholstery, mattress ticking, panel fabric and other items are formed of natural or synthetic fibers and then treated with fire-retardant chemicals. (See, for example, U.S. Pat. No. 6,309,565). It is also known in the textile industry to produce fire retardant fabrics using inherently fire retardant yarns made of modacrylic, flame resistant rayon, oxidized polyacrylonitrile fiber (OPF) to name a few.
US Pat. Publ. No. 2012/0255128 (U.S. '128) describes a fire retardant (or resistant) (FR) fabric for use as a fire retardant barrier. The FR barrier of U.S. '128 consists of a knit fabric fire barrier including a looped terry knitted fabric with a jersey side and a looped terry side, the jersey side including a fire retardant yarn and a meting yarn and the looped terry side including a fire retardant yarn. According to this patent application, the loops in the jersey side are very high loops (between 4 mm and 8 mm). The loops and melting yarn are essential elements of U.S. '128. These two essential elements of the fabric disclosed in U.S. '128, however, represent two major disadvantages. First, the terry loops or tuck stitching used in U.S. '128 restrict stretch of the fabric to less than 20%. Any more stretch would thin the fabric and substantially reduce its FR effectiveness. The limited stretch of the fabric of U.S. '128 makes it impractical (or very expensive) to produce in a sock fabric, as the fabric manufacturer would need a custom machine for each mattress size. Second, the melting yarn is liquefied the insulating structure of the fabric collapses which reduces the barrier's capability to reflect and flame also it speeds up the disintegration of strengthening fiber.
U.S. '128 teaches that the current stretchable knit products do not pass of the 16 CFR 1633 test because of the light weight of the products. U.S. '128, however states that an increase in weight significantly reduces the feel of the mattresses.
U.S. '128 also includes a tuck stitch in the fabrics disclosed therein. All current knit fabrics have some stretch, however the fabrics used to cover foam and/or latex have low stretch due to their use of tuck-stitch fabric construction. Current designs require tuck-stitch fabric construction to prevent the fabric from stretching open and reducing the flame barrier performance, thus, failing the 16 CFR 1633 requirements. The tuck-stitch fabric construction is also impractical to produce a one-size fits all sock form of the fabric for any type of mattress size.
Thus, what is needed is a comfortable flame resistant fabric with improved performance during the 16 CFR 1633 test and that it may be used without modification on a wide range of mattress sizes.
Presently, no stretchable knit product has passed the 16 CFR 1633 requirements.
In view of the foregoing, a new and innovative fire resistant knit that overcomes the deficiencies of the prior art is needed.